mozrunner
Reliable start/stop/configuration of Mozilla Applications (Firefox, Thunderbird, etc.)
Decision gist · record as of 2026-08-14
Yes, if you need to automate Mozilla application control in testing or CI/CD. Low install friction, active maintenance, no known vulnerabilities, and broad Python version support (3.8–3.13) make it a safe choice. The copyleft license is standard for Mozilla projects and poses no barrier to most use cases. Verify that your target Firefox/Thunderbird versions are compatible and that your deployment environment can support the package's Mozilla dependencies.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.8 or later; target Mozilla application must be installed on the system.
- Low friction to install; distributed as a pure-Python wheel.
- Actively maintained with recent release.
License · maintenance · safety
MPL 2.0 (copyleft) — Licensed under Mozilla Public License 2.0 (copyleft). Derivative works and modifications must be released under MPL 2.0; proprietary use of unmodified binaries is permitted, but source changes require reciprocal licensing.
last release 2026-03-26 (141 days)
0 known vulnerabilities (OSV.dev, 2026-08-14) · 246,275 downloads/mo, #8,714 on PyPI
Alternatives
Verify before relying
pip install mozrunner
from mozrunner import FirefoxRunner
runner = FirefoxRunner()
runner.start()
runner.stop()- Whether mozrunner requires Firefox or other Mozilla applications to be pre-installed on the system
- Whether it supports headless browser operation or requires a display
- Specific version compatibility constraints with Firefox/Thunderbird versions
What it is and what it does
Mozrunner is a Python library for programmatic control of Mozilla applications. It abstracts the complexity of launching, configuring, and managing Firefox, Thunderbird, and other Mozilla tools as subprocesses, handling process lifecycle, profile management, and configuration injection. It's part of the larger Mozilla Mozbase toolkit and is commonly used in automated testing, CI/CD pipelines, and browser automation scenarios where you need reliable, repeatable control over application startup and shutdown.
The package depends on six Mozilla libraries (mozdevice, mozfile, mozinfo, mozlog, mozprocess, mozprofile) that handle complementary concerns like device interaction, file operations, system introspection, logging, and profile management. It supports Python 3.8 through 3.13 and carries no known security vulnerabilities. The copyleft license (MPL 2.0) means any modifications you make must be released under the same license, though using the unmodified package in proprietary code is permitted.
Use it for
- Automated browser testing: launch Firefox with specific profiles and configurations for test suites
- CI/CD integration: reliably start and stop Firefox instances in build pipelines
- Process lifecycle control: manage Firefox startup, shutdown, and configuration injection programmatically
- Multi-instance testing: manage multiple concurrent Firefox processes with isolated profiles
- Browser compatibility testing: start different Firefox versions with consistent configuration
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you need to automate Mozilla application control in testing or CI/CD.
Low install friction, active maintenance, no known vulnerabilities, and broad Python version support (3.8–3.13) make it a safe choice. The copyleft license is standard for Mozilla projects and poses no barrier to most use cases. Verify that your target Firefox/Thunderbird versions are compatible and that your deployment environment can support the package's Mozilla dependencies.
Install
mozrunner on PyPI
Before you install
Low friction to install; distributed as a pure-Python wheel. Actively maintained with recent release. Depends on six Mozilla packages (mozdevice, mozfile, mozinfo, mozlog, mozprocess, mozprofile) that handle complementary concerns.
Requires Python 3.8 or later; target Mozilla application must be installed on the system.
License in practice
Licensed under Mozilla Public License 2.0 (copyleft). Derivative works and modifications must be released under MPL 2.0; proprietary use of unmodified binaries is permitted, but source changes require reciprocal licensing.
Quickstart
pip install mozrunner
from mozrunner import FirefoxRunner
runner = FirefoxRunner()
runner.start()
runner.stop()Verify before relying
- Whether mozrunner requires Firefox or other Mozilla applications to be pre-installed on the system
- Whether it supports headless browser operation or requires a display
- Specific version compatibility constraints with Firefox/Thunderbird versions
Package facts
| License | MPL 2.0 copyleft |
| Python support | Supports the current Python release >=3.8 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 6 packagesmozdevicemozfilemozinfomozlogmozprocessmozprofile |
| Maintenance | Actively maintained 141 days since the last release |
| First released | |
| Downloads | 246,275 / month, #8,714 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Environment :: ConsoleIntended Audience :: DevelopersLicense :: OSI Approved :: Mozilla Public License 2.0 (MPL 2.0)Natural Language :: EnglishOperating System :: OS IndependentProgramming Language :: PythonProgramming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Topic :: Software Development :: Libraries :: Python Modules |
Evidence: mozrunner-8.4.0-py2.py3-none-any.whl
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See also dockerflow · mozdebug · mozdevice · mozprofile · honcho · fuzzfetch · mozprocess · mozinfo · mozfile · mozilla-version